Long ago I used ceramic cone insulators too, but for decades I've used simple 1/4" acrylic tubes. They insure that nothing in the wall comes in contact with the feed line and eliminate the mechanical joints at either end of the feed-through (I solder the feed line connections). A small 1/4" hole accommodates each tube and extend about 1/2" out of both sides of the wall. A few wraps of tape around the ends keep them from sliding out of place. They are not very visible either.
I've used acrylic in a number of very high RF voltage insulator applications with no sign of failure. There's a reason why we put fences around commercial transmitting antennas and take care to avoid touching antennas on ships! RF burns are terribly painful. They're deep and they're nasty. Many of us O.T.s learned about them using a pencil to draw an RF arc from the plate cap of a transmitting tube "for fun" :-) I can still remember the deep, throbbing pain from a little black burn that lasted for days right at the spot where the metal eraser ferrule was touching my skin the very LAST time I did that, Hi! 73, Ron AC7AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
